The present invention relates to a shaft for use in a machine to perform at least one operation. In particular, it relates to a light weight, low cost, shaft assembly having a hollow, tubular, shell like portion containing a hardened, moldable material within its core in communication with at least one molded feature on the outside or at the end of the tubular shell like portion.
Cross reference is made to the following application filed concurrently herewith: U.S. application Ser. No. 09/293,346 entitled xe2x80x9cHollow Shafts with Gas Assist Moldingxe2x80x9d by Robert D. Russell.
While the present invention has utility in apparatus comprising various mechanical components, it has particular application and will henceforth be described with reference to electrostatographic reproducing apparatus. Briefly, and as illustrated in FIGS. 1 and 2, in electrostatographic printing apparatus commonly in use today a photoconductive insulating surface 10 which is typically the surface of a rotatably drum is charged to a uniform potential by a charge corotron 12 and thereafter exposed to a light image of an original document 15 to be reproduced on an exposure platen 16 by means of exposure lamp 17, the exposure discharging the photoconductive insulating surface in exposed or background areas creating an electrostatic latent image on the photoconductive insulating surface of the document. A developer unit 20 is which corresponds to the image areas contained within the apparatus and has developer material to developed the electrostatic latent image. Typically, the developer material has charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles and during development, the toner particles are attracted from the carrier particles to the charged areas of the photoconductive insulating surface. The developed image on the photoconductive insulating layer is subsequently transferred at a transfer station 24 to a support surface, such as copy paper which is fed by feeder 22 to provide intimate transfer contact between the insulating area and the copy paper. The toner image on the copy paper is subsequently, permanently affixed on the copy paper by the application of heat and/or pressure in a fuser 23. Subsequent to the transfer of the toner image to the support surface, any residual toner remaining on the photoconductor is cleaned by a cleaner 19 in preparation for the next imaging cycle. FIG. 2 illustrates the claim shell nature of this machine having a lower frame member 25 and an upper frame member 26 which has two shafts, 27, 28 in the copy sheet transport system. For example, the shafts 27 and 28 may be paper path nip shafts.
Alternatively, the electrostatic latent image may be generated from information electronically stored or generated in digital form which afterwards may be converted to alphanumeric images by image generation, electronics and optics. For further information on such apparatus, attention is directed to U.S. Pat. No. 4,372,668 to Malachowski et al., and U.S. Pat. No. 4,660,963 to Stemmle et al.
In these machines, shafts are typically used to provide a variety of features performing functions within the machines. For example, shafts typically have gears, rolls, pulleys or other drive mechanisms mounted thereon to enable driving various parts or systems in the machine. For example, the shafts may be paper path nip shafts. In addition, the shafts may have retention or location features such as, snaps, fitting elements or stops or may contain other features such as bearings, bushings, rollers, journals and O-rings. Initially, the shafts were typically made from solid materials such as, metals like, steel and aluminum, and the individual functional features or elements such as rollers or gears were individually mounted to the shaft and secured thereto. Typically, this assembly process was manually completed as it did not readily lend itself to automated assembly. While satisfactory in many respects, such shaft assemblies were both heavy and costly in that solid shafts contained more metal and therefore cost more. Each of the individual functional features has to be separately manufactured, separately assembled onto the shaft assembly, all of which increased both materials and assembly time and cost particularly when most of the functional features had to also be located and fixed by way of set screws or other such device to the shaft. Alternatively, the functional features have been formed on metal stock material by such conventional metal working techniques as turning, milling and grinding. In addition, the weight of such shaft assemblies provided a high moment of inertia which necessitated increased drive power requirements.
Referring now to FIGS. 5 and 6, a shaft assembly 7 is shown for use in guiding paper sheets through a copy or printing machine. The shaft assembly 7 is manufactured by first providing a 8 millimeter stainless steel shaft 2 having a generally cylindrical shape and including grooves 5 for placement of E-rings to secure the shaft assembly 7 within the printing machine. Knurls 3 are machined into the periphery 4 of the shaft 2. Rollers 8 are fitted onto the shaft 2 at the knurls 3 by pressing the hollow rollers 8 onto the shaft 2. This prior art shaft assembly is both heavy and expensive. The use of a solid steel shaft adds significant weight to the shaft assembly and the machining requirement of the knurls as well as the assembly time to assemble the rollers 8 to the shaft 2 adds manufacturing and assembly costs to the shaft assembly 7.
Attempts have been made to provide shaft assemblies with reduced weight and manufacturable at a lower cost. One such attempt is the use of a two-component or composite shaft process. The composite shaft process may be more fully understood with reference to U.S. Pat. No. 5,439,916, U.S. Pat. No. 5,876,288, and U.S. Pat. No. 5,683,641, all to Jaskowiak and assigned to the same assignee as the present invention. The composite shaft process utilizes a hollow metal tube to which slits or holes are machined through the wall of the tube. The tube is placed in a molding machine and hard moldable material is injected into the opening on the end of the tube and permitted pass through the apertures in the periphery of the tube to fill functional features formed in a mold cavity. While the composite shaft process provides for improved performance and reduce costs, the use of a cylindrical metal tube adds costs to the shaft assembly and the requirement of machining the apertures in the periphery of the tube further adds costs to the process. Further, the design of the composite shaft is limited by the fact that the tube is typically cylindrical with a generally uniform outer periphery.
The present invention is directed to alleviate at least some of the aforementioned problems.
The following disclosures may be relevant to various aspects of the present invention:
U.S. Pat. No. 4,101,617 to Friederich discloses a method for making a hollow shaped body from a thermoplastic resin by injection molding. The method includes injecting an amount of molten resin sufficient for the preparation of the hollow shaped body through an injection nozzle into a mold through an injection aperture in the mold. Gas is injected under pressure through the injection nozzles and aperture to expand and distribute the molten resin over the interior surfaces of the mold.
U.S. Pat. No. 3,632,263 discloses a device for blowing a hollow thermoplastic body manufactured according to the extrusion-blowing process from a continuous vertically extruded tubular parison cut into sections enclosed into separate split moulds disposed beneath the extrusion head. This device is characterized in that a blowing chamber of relatively reduced dimensions is formed in the two mould halves or sections and adapted to retain therein one open end of the parison section when the mould is closed, and that a compressed-gas injection nozzle connected to a source of compressed gas opens into said blowing chamber and is so arranged that the gaseous jet issuing from said nozzle is directed towards said open end of the parison.
U.S. Pat. No. 3,659,434 to Wolfe discloses a tubular shaft having an outer metallic, tubular member filled with resin. The tube is cut to a preselected length and has a central passageway defined by the inner wall of the metal tube. The tube is heated and swaged and an injector nozzle is positioned at one end and resinous material is pumped into the cavity. See Col. 2, lines 26-61.
U.S. Pat. No. 3,659,434 discloses tubular shafting having a metallic outer tubular member and a cellular resinous core is both kinetically and dynamically balanced by drilling holes in the outer metallic tubular member at locations where additional weight is required to balance the shafting. A predetermined amount of molten metal is poured through the drilled holes into the internal portion of the tubular shafting. The molten metal flows through passageways in the cellular resin core and solidifies against the inner wall of the outer metallic tubular member. The passageways formed in the cellular resin are filled with a similar cellular resin and the holes in the outer metallic tubular member are suitably plugged.
U.S. Pat. No. 3,707,113 discloses a piston for use in an axial and/or radial piston hydraulic translating unit, comprising a hollow skirt portion having inner surfaces defining a cavity and filled with a lightweight material, the material retained in place by discontinuous irregularities in the surface of the hollow skirt which mechanically interlock the filler material within the piston.
U.S. Pat. No. 3,716,612 discloses a method is described for making articles of plastic materials; for example, plastic bottles, from a composite of synthetic thermoplastics. Two or more such resinous materials, which have distinct polymeric and physical characteristics, are combined in a way such that they are present in the article in separate phases possessing an apparent plurality of generally commensurately and spirally extending layers of the said resinous materials and in a manner adapted to take full advantage of the resulting combination of properties.
U.S. Pat. No. 3,968,561 discloses a hollow structural member formed of thin sheet steel is formed with one or more longitudinal joints and the interior is filled with a rigid lightweight synthetic plastics foam such as polyurethane. Each joint includes folded lips or flanges which are designed to provide a restricted clearance or gap into which the foaming material penetrates and changes from a cellular to a non-cellular composition and also provides an adhesive bond at each joint and a moisture proof seal.
U.S. Pat. No. 4,038,359 discloses a shaft seal of the type including a metal case and a polytetrafluoroethylene sealing element, is provided with an auxiliary sealing lip by providing a radial flange of the metal case with a plurality of circumferentially spaced-apart apertures therethrough and molding an annular filler ring of synthetic rubber in the space between the sealing element and the metal case such that the rubber also flows through the apertures to the other side of the radial flange of the metal case and forms an auxiliary lip there. The filler ring chemically bonds to the metal case and mechanically bonds to the sealing element to lock the sealing element in place while also forming an auxiliary lip.
U.S. Pat. No. 4,063,429 discloses a pipeline retard, support and protection method wherein a fast-setting expandable foam is placed in a trench at spaced locations below and around a pipeline to create spaced retards and support pads in situ. Each retard and/or support pad is created in the absence of forms or other foam molding means for the expanding foam. The retards may be keyed to the trench walls and base for securement. The system is also adaptable to encapsulating a portion of the pipeline which transverses a roadbed.
U.S. Pat. No. 4,169,304 discloses one or more thin metal sheets are formed as a hollow shell having a longitudinal load-bearing axis. The thin-walled hollow shell is filled with a core of a plastic foaming material including a suitable foaming agent which foams to fill the shell and to exert a force on the shell radially outwardly of the longitudinal axis thereby forming a solid composite column. The radially outward force deflects the shell and permanently places the shell in lateral tension to increase the load bearing capability of the column. When more than one sheet is used, the elongated edge portions of the sheets are configured to loosely interfit with one another when the shell is initially formed, and the plastic foaming material causes a positive locking of the interfitted edge portions. Thus thin, non-load bearing gauge aluminum is converted into a load bearing structural element.
U.S. Pat. No. 4,216,634 discloses a foam filled metal shell building column for dwellings and the like comprises one or more thin metal sheets formed as a hollow shell having a longitudinal load-bearing axis. The thin-walled hollow shell is filled with a core of a plastic foaming material including a suitable foaming agent which foams to fill the shell and to exert a force on the shell radially outwardly of the longitudinal axis thereby forming a solid composite column. The radially outward force deflects the shell and permanently places the shell in lateral tension to increase the load bearing capability of the column. When more than one sheet is used, the elongated edge portions of the sheets are configured to loosely interfit with one another when the shell is initially formed, and the plastic foaming material causes a positive locking of the interfitted edge portions. Thus thin, non-load bearing gauge aluminum is converted into a load bearing structural element.
U.S. Pat. No. 4,256,685 discloses an improved method is described for varying the profile as seen in cross section of an elongated extrudate article. The method provides for varying the profile of an extrusion orifice while an extrudate stock material is being forced through the orifice. An elongated extruded article is formed having a varying profile conforming to the variations in the profile of the extrusion orifice.
U.S. Pat. No. 4,372,668 discloses a reproducing apparatus with a stationary optical system, a reciprocating platen to transport a document across the stationary optical system, a copy sheet feeding apparatus and a copy sheet registration apparatus to feed a copy sheet in synchronism with the transport of a document by the platen. The platen has mechanical means such as a linear cam to actuate the copy sheet registration apparatus and the copy sheet registration apparatus is responsive to the platen actuating means to directly actuate the copy sheet registration apparatus.
U.S. Pat. No. 4,380,442 discloses a rotary flexible coupling has two interleaved sets of input and output driver blocks connected to input and output flanges, respectively. First and second tires of inelastic material are spaced radially inwardly and radially outwardly from the blocks. Each block is connected to each tire by a cylindrical segment of a cylindrical layer of elastomeric material and torque is transmitted from the input blocks to the output blocks via the elastomeric layers and the tires.
U.S. Pat. No. 4,474,717 discloses a method and apparatus for making a twin-wall internally corrugated plastic structural part provided with a smooth, dense, solid, thin walled, non-cellular skin comprising injecting a thermoplastic or resin material into a pair of closed mold members which define a sealed cavity. A small amount of plastic material is initially injected into the cavity with the material impinging upon and being dispersed over the mold members thereby forming a generally continuous thin skin substantially the mold surfaces. Thereafter, successively and intermittently injecting an inert gas under pressure through one mold member during continued injection of the plastic material into the cavity thereby pressurizing the skin against the walls of the mold cavity and progressively co-mingling the inert gas under pressure and the inwardly flowing plastic material as both enter the cavity until the cavity is filled with an internal corrugated body integral with and bonded to the skin. Further steps include cooling the twin-wall internally corrugated structural part to permit the same to solidify as an integral unit and venting the mold cavity to atmosphere to relieve pressure from the corrugated plastic structural part. The intermittent injection of the inert gas introduces minute amounts of pressurized gas into the continuously injected plastic material.
U.S. Pat. No. 4,555,225 discloses a method and apparatus for making a twin-wall internally corrugated plastic structural part provided with a smooth, dense, solid, thin walled, non-cellular skin comprising injecting a thermoplastic or resin material into a pair of closed mold members which define a sealed cavity. A small amount of plastic material is initially injected into the cavity with the material impinging upon and being dispersed over the mold members thereby forming a generally continuous thin skin substantially the mold surfaces. Thereafter, successively and intermittently injecting an inert gas under pressure through one mold member during continued injection of the plastic material into the cavity thereby pressurizing the skin against the walls of the mold cavity and progressively co-mingling the inert gas under pressure and the inwardly flowing plastic material as both enter the cavity until the cavity is filled with an internal corrugated body integral with and bonded to the skin. Further steps include cooling the twin-wall internally corrugated structural part to permit the same to solidify as an integral unit and venting the mold cavity to atmosphere to relieve pressure from the corrugated plastic structural part. The intermittent injection of the inert gas introduces minute amounts of pressurized gas into the continuously injected plastic material.
U.S. Pat. No. 4,600,548 discloses a method of forming the primary core of a concrete pipe. A steel cylinder is disposed vertically on the base of the pipe forming machine. A conventional rotary packerhead having a diameter less than the inner diameter of the steel cylinder is lowered concentrically to the bottom thereof. Concrete is then introduced within the steel cylinder through the upper end thereof. The packerhead is rotated to force the concrete into the annular gap between the packerhead and the steel cylinder. As the primary core is formed, the packerhead is raised and rotated while concrete is introduced within the steel cylinder, thereby forming a primary core consisting of a steel cylinder having an inner lining of concrete. In an alternative embodiment, the steel cylinder is completely embedded within the concrete.
U.S. Pat. No. 4,988,472 discloses a method of inserting a piece into a mold for molding a mouth of a preform which utilizes a cavity surface of a mold for molding an outer side of a mouth and a cavity recess for molding a support ring to support a heat resistant short tubular piece within the mold, wherein spacers in the form of projections are integrally formed at fixed intervals on the outer side of the piece and the fore end of the projection. The piece is inserted into a central portion of an opened mold for molding a mouth, after which the mold is closed, the projections are inserted into the cavity recess, the spacers are pressed against the cavity surface, and the piece is held and secured to the central portion of the cavity by the mold through the spacers.
U.S. Pat. No. 5,439,416 discloses a shaft assembly comprising an elongated member having at least a portion which is hollow, tubular, shell like having an inside surface defining a shaft core and an outside surface defining a shaft functional surface, the shaft core being filled with a hardened, moldable material, and the shaft functional surface having at least one functional feature thereon, which is of hardened, moldable material integrally molded with the hardened, moldable material in the shaft core. In a preferred embodiment the shaft assembly is rotatable and has at least one molding aperture gate extending through the shaft from the inside surface to the outside surface which is filled with hardened, moldable material which connects the hardened material in the shaft core and functional feature.
U.S. Pat. No. 5,533,553 discloses a method for molding a lead screw for converting a rotational movement into a linear movement, there are provided a method and a die assembly which may involve the steps of forming a plurality of holes in a wall of a tube in a spiral arrangement, preparing a metallic die assembly provided with a cavity defining a thread groove adapted to form the thread crest matching in position with an array of the holes, placing the tube in the cavity, and injecting synthetic resin material into the cavity so that the synthetic resin material may flow in two separate flows, one flowing inside the core tube, and the other flowing along the outer surface of the core tube. The thread crest is connected to the synthetic resin material filled in the core tube, and can be securely attached to the core tube. Optionally, an annular rotor may be fitted onto the base end portion of the lead screw. The synthetic resin material is first filled into the annular gap defined around the annular rotor before it is filled into the interior of the annular rotor so that the rotor may be prevented from being damaged by the tensile stress produced by internal pressure acting on the annular rotor.
U.S. Pat. No. 5,683,641 discloses a shaft assembly comprising an elongated member having at least a portion which is hollow, tubular, shell like having an inside surface defining a shaft core and an outside surface defining a shaft functional surface, the shaft core being filled with a hardened, moldable material, and the shaft functional surface having at least one functional feature thereon, which is of hardened, moldable material integrally molded with the hardened, moldable material in the shaft core. In a preferred embodiment the shaft assembly is rotatable and has at least one molding aperture gate extending through the shaft from the inside surface to the outside surface which is filled with hardened, moldable material which connects the hardened material in the shaft core and functional feature.
U.S. Pat. No. 5,876,288 discloses a shaft assembly comprising an elongated member having at least a portion which is hollow, tubular, shell like having an inside surface defining a shaft core and an outside surface defining a shaft functional surface, the shaft core being filled with a hardened, moldable material, and the shaft functional surface having at least one functional feature thereon, which is of hardened, moldable material integrally molded with the hardened, moldable material in the shaft core. In a preferred embodiment the shaft assembly is rotatable and has at least one molding aperture gate extending through the shaft from the inside surface to the outside surface which is filled with hardened, moldable material which connects the hardened material in the shaft core and functional feature.
U.S. patent application Ser. No. 09/195,959 discloses a shaft assembly including an elongated member having at least a portion which is hollow having an inside surface defining a shaft core is provided. The shaft assembly has an outside surface defining a shaft functional surface. The shaft core is filled with a hardened, moldable material. The shaft functional surface has at least one functional feature thereon which is of hardened, moldable material integrally molded with the hardened, moldable material in the shaft core. The coefficient of thermal expansion of the hollow portion and the shrink rate of the moldable material are selected to provide intimate contact between the hardened moldable material and the hollow portion.
EPC 0-248-567 discloses a discloses a method of making a hand tool for percussive use. The method includes locating a hollow elongate handle member in a head shaped cavity so that a portion of the handle member protrudes from the cavity. A settable polymeric material is introduced into the cavity and into the inside of the handle member. The material forms the head of the hand tool in the mold cavity.
Japan Application No. 83-113619 discloses a functional shaft composed of a cylinder, a functional member and a synthetic resin section. The synthetic resin section includes sections inside and outside the cylinder and both are connected to each other through apertures in the cylinder.
Japan Application No. 58-94619 discloses a power transmission shaft including a cylindrical body and synthetic resin portions which are located inside and outside the cylindrical body and which are integrally provided with the cylindrical body through holed in the cylindrical body.
All the above references totally incorporated herein by reference.
Additional progress in terms of cost and weight of the shaft assemblies has been observed in certain machines which use hollow drive shafts with molded or otherwise separately fabricated functional features such as, gears and rolls which are then manually placed on the shaft and secured in position.
In particular, in one embodiment of the invention, a shaft assembly including an elongated member having at least a portion which is hollow having an inside surface defining a shaft core is provided. The shaft assembly includes a rotatable, torque transmitting elongated member defining a portion thereof which is hollow having an inside surface and defining a shaft core. The shaft has an outside surface including a torque transmitting portion and a functional feature portion. The elongated member defines an aperture gate extending from the inside surface to the outside surface. The elongated member also defines a hardened, moldable material. The material extends from the inside surface through the aperture gate. The material is secured to at least a portion of the outside surface.
In another embodiment of the invention, an apparatus including mechanical components capable of performing at least one operation requiring the use of a shaft assembly is provided. The shaft assembly includes a rotatable, torque transmitting elongated member defining a portion thereof which is hollow having an inside surface defining a shaft core. The shaft has an outside surface including a torque transmitting portion and a functional feature portion. The elongated member defines an aperture gate extending from the inside surface to the outside surface. The shaft assembly also includes a hardened, moldable material. The material extends from the inside surface through the aperture gate. The material is secured to at least a portion of the outside surface.
In another embodiment of the invention, a process for making a rotatable shaft assembly for transmitting torsional torque having at least one functional feature on an outside surface of the shaft. The process includes the steps of gas injection molding an elongated member having at least a portion which is hollow having an inside surface defining a shaft core and an outside surface defining a shaft functional surface, providing the elongated member with an aperture gate extending from the inside surface to the outside surface, placing the hollow portion in a mold which has a cavity for the at least one functional feature on the outside surface of said portion, filling the mold with a hardenable, moldable material, flowing the moldable material through the shaft core and cavity, permitting the moldable material to harden to form the functional feature, and removing the shaft assembly with the functional feature from the mold.